1. Field of the Invention
This invention relates to pile footings, particularly to a novel precast concrete pile and a method of placing a pile in the ground by which a foundation can be reinforced.
2. Related Art
It is known in the art that pile footings are driven into the ground to support and strengthen the superstructures. There is a type of reinforced concrete pile which is of uniform cross section with a tapered end and which can be driven into the ground directly by pile driving equipment. As the pile cross section is uniform, the friction between the pile and the surrounding earth is insufficient to prevent the sinking of the pile due to high load, earthquake, etc., unless the pile is driven until it reaches a hard bearing stratum. The sinking of the foundation easily happens in the loose earth, such as that area around coast-lines seashores, etc.
There is also another type of pile called a "cast-in-place" pile which includes a casing and an iron core. They are driven into the ground together, and, once in place, the core is pulled, and a concrete mixture is poured into the casing about 4 to 12 feet height. Then the iron core is again put into the casing, and subsequently the casing is pulled out about 2 to 4 feet. The concrete mixture is compressed by driving the core with a pile driver so that an enlarged base is formed. Thereafter, the iron core is completely pulled out, and the casing is filled with a concrete mixture. Finally the casing is pulled out. The formed pile has a uniform cross section structure and an enlarged base. However, such pile footing is still unsatisfactory for strengthening the foundation of the superstructure.